analysis optimization of switchyard earthing system using
TRANSCRIPT
Journal of Applied Science and Advanced Technology Journal Homepage : https://jurnal.umj.ac.id/index.php/JASAT
Corresponding author.
E-mail address: [email protected] DOI: https://dx.doi.org/10.24853/JASAT.2.3.77-82
Analysis Optimization of Switchyard Earthing System Using MATLAB Deni Almanda1*, A I Ramadhan2 1Department of Electrical Engineering, Faculty of Engineering, Universitas Muhammadiyah Jakarta, Indonesia 2Department of Mechanical Engineering, Faculty of Engineering, Universitas Muhammadiyah Jakarta, Indonesia
A R T I C L E I N F O A B S T R A C T
JASAT use only:
Received date : 19 January 2020
Revised date : 21 February 2020
Accepted date : 28 March 2020
Keywords:
switchyard earth system
grid
ground rod
optimization
One of the main factors in securing an electric power system is the earthing system.
The earthing system in the generating unit is closely related to the switchyard.
Switchyard earthing system analysis is done by adjusting the grid distance and
ground rod length to get the most optimal quality and cost combination. The
definition of optimal conditions in this case is limited to circumstances where there
is a combination of quality that does not exceed the technical tolerance threshold
and has cost efficiency. The analysis of the switchyard earthing system was taken as
a case study. Calculation results and analysis concluded that the grid distance of 23
m and the length of the 6 m ground rod is the best choice in the optimization of this
earthing system by meeting the safety quality criteria for earth resistance is Rg =
0.13806 Ω less than 0.5 Ω with a minimum cost of Rp. 1,220,104,730.Technical
standards are carried out based on IEEE Std 80-2000. Calculations for obtaining
technical parameters and costs are carried out one-by-one in the range of grid
spacing and length of certain ground rods to determine the optimum point using
MATLAB-GUI as a programming tool and MATLAB R2011a as a tool
mathematical computing.
© 2020 Journal of Applied Science and Advanced Technology. All rights reserved
INTRODUCTION
Earthing system or commonly referred to as a
grounding system is a security system for devices
relating to soil type resistance, earthing resistance
also has a large effect on the size of the soil type
resistance, the higher the grounding resistance value
the higher the soil type resistance. Measurement of
soil type resistance is usually done by measuring
soil resistance and the level of security in the
earthing system [1-10].
Table 1. Soil Characteristics [2]
Type of Soil
Average Soil
Resistance
(Ω ·m)
Wet Organic Soil 101
Moist Land 102
Dry soil 103
Hard Soil Layer 104
Specifically, the safety function of the earthing
system can be related to three interrelated aspects,
namely (1) limiting voltage due to lightning, wave
lines, or short circuit with high voltage lines, (2)
stabilizing voltage, (3) providing a way to facilitate
operation over current device [11-16]. The total
length of conductor planting is the sum of the
horizontal (grid) and vertical (rod) conductors with
the following equation (1):
LT = LC + LR (1)
Wherein:
LC : total length of the grid conductor (m)
LR : total length of conductor rod (m)
Knowing the number of grid conductors and the
length of the grid conductors in the direction of the
grid planting, according to the following equation
(2):
(2)
From equation (2) above, to get the length of the
conductor which is affected by the grid distance, the
number of conductors Nx and Ny becomes Nx =
Journal of Applied Science and Advanced Technology Volume 2 No. 3 April 2020 Website : https://jurnal.umj.ac.id/index.php/JASAT ISSN : 2622-6553 (Online)
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Lx/D and Ny = Ly/D, so the above equation
becomes the following equation:
(3)
Where:
Ny : total grid conductor in Y direction
Nx : total grid conductor in X direction
Ly : length of conductor Y direction (m)
Lx : length of conductor X direction (m)
D : grid conductor distance (m)
Initial Parameter Data
The optimization of the earthing system is based on
the influence of the grid spacing and the length of
the ground rod in finding the optimal earthing
system value in terms of safety and the total cost to
be incurred [17]. The data that need to be included
in determining the optimization of the earthing
system design are obtained from IEEE Std 80-2000
[17] and the Cilacap Adipala Power Plant Data with
a Tolerance Touch Voltage of 240 V as contained in
the contract documents. In this case study the data
used are 777.8 MVA X” generator d = 21.4%, 800
MVA transformer voltage 22/500 kV, Xt = 16.19%,
then the If value of the 500 kV voltage side fault is
as follows Fig. 1.
Fig. 1. Single Line Switchyard Diagram 500 kV
To run the program, the initial parameter data will
be used as input in the analysis of earthing system
optimization in the Matlab program. Before the
program reads the input data, the program first reads
the length of the ground rod, which was first
included in the Matlab program.
Optimization
Optimization is the results achieved in
accordance with the wishes, so optimization is the
achievement of the results according to expectations
effectively and efficiently. Much optimization is
also defined as a measure by which all needs can be
met from the activities carried out [18].
To get the optimal design, it can be done by
fulfilling the following minimum cost functions:
(4)
From the cost function above, to get the minimal
cost function influenced by grid distance, equation
(1).
(5)
EXPERIMENTAL METHOD
In analyzing Earthing performance analysis by
taking conductor length data, general system data
parameters and soil characteristics. In the case of a
simple performance analysis, the program requests
data related to the length of the grid conductor,
number of ground rods, data about switchyard,
general data related to the power system for safety
criteria, conductor size and materials and others.
RESULTS AND DISCUSSION The conductor used in the design of this
earthing system is Copper, annealed soft-drawn,
obtained from the calculation of the grid conductor
size 177,4066 mm2, then conductors with a cross-
sectional area of 240 mm2. The reduction factor (Cs)
value equals 0.71264 is used to calculate the touch
voltage and tolerance step voltage. The touch
tolerance value is 240,0002 V and the tolerance step
voltage is 612,0009 V. As for the maximum grid
current with a disturbance current rms value of 5.7
kA, the maximum grid current value is 7506.33 A.
Deni Almanda, A I Ramadhan: Analysis Optimization of Switchyard Earthing System Using MATLAB Journal of Applied Science and Advanced Technology 2 (3) pp 77-82 © 2019
79
Fig. 2. Display of the Earthing System Optimization
Calculation Program
Fig. 3. Grid Distance Graph (D) against RgIG
Fig. 4. Display Program Distance Range Grid
Results
Fig. 5. (a) Effect of Grid Distance on Em, (b) Effect
of Grid Distance on El
Fig. 6. Graphic Effect of Ground Rod Length on
grid distance and cost
Fig. 7. Graph of Results of Earthing System
Optimization Program
Journal of Applied Science and Advanced Technology Volume 2 No. 3 April 2020 Website : https://jurnal.umj.ac.id/index.php/JASAT ISSN : 2622-6553 (Online)
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Table 2. Analysis Optimization of Switchyard Earthing System Using MATLAB
CONCLUSION
Based on the results of the optimization
program using Matlab GUI and Matlab
R2011a, it can be concluded that the grid
distance of 23 m and the length of the 6 m
Ground rod provides the most optimal
grounding system design results, with a safety
quality for Earthing Resistance (Rg) of
0.13806Ω smaller than The maximum limit of
Earthing Resistance is 0.5 Ω (IEC 60694) and
the value of the mesh voltage is smaller than
the touch tolerance voltage (Em = 239.1854 V
<Es_tol = 240,0002 V) and the tolerance step
voltage is more than Rp. 1,220,104,730.
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